fix(markdown-mode): prevent block change from stripping numbers (#140)

* fix: prevent block change from stripping numbers

fixes #69

* add matchLeadingBlockCharacters tests

* docs(commands): reseat TODOs for match regex

* fix(commands): add support for all ordered list markers in matchLeadingBlockCharacters

Co-authored-by: Ben Kelly <b-kelly@users.noreply.github.com>

Author: dancormier

src/commonmark/commands.ts

@@ -192,11 +192,20 @@ function setBlockType(
 /**
  * Returns any block formatting characters (plus trailing space) at the very start of the passed text
  * @param text The text to check for leading block characters
+ * @internal
  */
-function matchLeadingBlockCharacters(text: string) {
+export function matchLeadingBlockCharacters(text: string) {
     // TODO this might be too aggressive... remove based on a whitelist instead?
-    // TODO HACK assumes all block types are non-letter characters followed by a single space
-    return /^[^a-zA-Z]+\s{1}(?=[a-zA-Z_*[!]|$)/.exec(text)?.[0] || "";
+    // Match ordered list markers; see https://spec.commonmark.org/0.30/#ordered-list-marker
+    let match = /^(\d+)(?:\.|\))\s/.exec(text)?.[0];
+
+    // If text is not an ordered list block, check for other block types
+    if (!match) {
+        // TODO HACK assumes all non-ordered list block types are non-letter characters followed by a single space
+        match = /^[^a-zA-Z0-9]+\s{1}(?=[a-zA-Z0-9_*[!]|$)+/.exec(text)?.[0];
+    }
+
+    return match || "";
 }
 
 /**

test/commonmark/commands.test.ts

@@ -521,4 +521,37 @@ some text`;
             });
         });
     });
+
+    describe("matchLeadingBlockCharacters", () => {
+        it("return no leading characters", () => {
+            const command = commands.matchLeadingBlockCharacters(
+                "42 shouldn't be returned"
+            );
+
+            expect(command).toBe("");
+        });
+
+        it("return ordered list leading characters", () => {
+            let command = commands.matchLeadingBlockCharacters("23. -ol item");
+
+            expect(command).toBe("23. ");
+
+            command = commands.matchLeadingBlockCharacters("23) -ol item");
+
+            expect(command).toBe("23) ");
+        });
+
+        it("return unordered list leading characters", () => {
+            const command = commands.matchLeadingBlockCharacters("- 1 ul item");
+
+            expect(command).toBe("- ");
+        });
+
+        it("return heading leading characters", () => {
+            const command =
+                commands.matchLeadingBlockCharacters("## Heading level 2");
+
+            expect(command).toBe("## ");
+        });
+    });
 });